Titanium master alloy for titanium-aluminum based alloys

ABSTRACT

A process is disclosed for the electro-refinement of titanium aluminides to produce titanium-aluminum master alloys which process is effective even in the presence of substantial amounts of aluminum and in the presence of ten (10) or more weight percent oxygen in the material(s) to be refined. The process is likewise effective without the addition of titanium chlorides or other forms of soluble titanium to the electrolyte bath comprising halide salts of alkali metals or alkali-earth metals or a combination thereof.

RELATED APPLICATIONS

This application claims the benefit, and priority benefit, of U.S.Provisional Patent Application Ser. No. 62/446,205, filed Jan. 13, 2017,the disclosure and contents of which are incorporated by referenceherein in its entirety.

BACKGROUND OF THE DISCLOSURE 1. Field of the Invention

The present disclosure relates to a method to produce titanium masteralloy for titanium-aluminum based metal alloys. The titanium-aluminumbased alloys can have a composition of Ti-(1-10)wt. % Al-X (where X=V,Sn, Fe, Nb, Mo, etc.). More particularly the disclosure is directedtowards various methods to electro-refine titanium aluminides for theproduction of titanium-(1-10)wt. % aluminum master alloy.

2. Description of the Related Art

Superior structural properties such as corrosion resistance, lightweight and high-melting point, make titanium and its alloys the materialof choice for many engineering applications.

However, the use of titanium and its alloys is limited due to high costassociated with their production. As of today, titanium alloys areproduced from titanium “sponge”, the product of a process known as the“Kroll Process”. In subsequent steps, aluminum and other alloying metalsmust be added to the sponge by using various melting processes.Therefore, the cost of titanium alloys is several times higher than theoriginal cost of titanium. For example, in one 2015 publication,titanium production cost is indicated to be $9.00/kg (Ma Qian andFrancis H. Froes, ed., Titanium Powder Metallurgy Science, Technologyand Application (Elsevier Inc., 2015), p. 37)) whereas the cost ofTi—Al—V is $17.00/kg.

Despite the cost of production, titanium and its alloys are the onlychoice for many engineering applications. 90% of titanium that is usedin the aerospace industry is used as titanium alloys. Accordingly, thereis a need for a new titanium alloy production process that reduces thecost significantly.

Fundamental theory teaches that Al, Mn, V, and Cr cannot be removed fromTi by electro-refining (Rosenberg et al. U.S. Pat. No. 6,309,595 B1).This is due to the similar electrical ionization potential of theseelements. Literature demonstrates that indeed Mn, V, and Cr cannot beremoved from Ti by electro-refining when present in substantial amounts(Dean et al. U.S. Pat. No. 2,913,378). Because the electrical ionizationpotential of Al is in between the potentials of Mn and V, it is clearthat Al also theoretically cannot be removed by electro-refining.Therefore, literature dissuades from the use of Al-containing Ti asprecursor material for electro-refining and advocates the removal of Alby other means prior to electro-refining (R. S. Dean et al. U.S. Pat.No. 2,909,473).

Moreover, literature teaches that the presence of a substantial amountof oxygen in the precursor material prevents the effective separation ofAl from titanium. In fact, literature teaches that when 5% oxygen ispresent, aluminum cannot be separated by electro-refining (R. S. Dean etal. U.S. Pat. No. 2,909,473). Contrarily, the current embodiments of thedisclosure require the presence of a substantial amount of oxygen (atleast 10 wt. %) in materials to be electro-refined.

Also, literature teaches that it is essential to add soluble titanium tothe electrolyte in the form of titanium chlorides when refining titanium(W. W. Gullet U.S. Pat. No. 2,817,631 and F. J. Schultz et al. U.S. Pat.No. 2,734,856). Titanium chlorides are produced by carbo-chlorination ofhighly purified TiO₂. Therefore, the use of these titanium chloridesadds more cost to the refining process.

Conventional titanium or titanium alloy production methods result insolid and dense products.

SUMMARY OF THE DISCLOSURE

With the present disclosure titanium-aluminum alloys (e.g. masteralloys) can be produced directly without requiring any alloying steps(e.g. melting processes), therefore considerably decreasing theproduction cost compared to currently used methods.

In one or more embodiments of the instant disclosure, the methodsprovide a simple and more economical way to produce titanium-aluminumbased alloys. With one or more embodiments of the instant disclosure,these methods do not require the addition of any soluble titanium (suchas titanium chlorides) to the electrolyte, which thereby further reducesproduction cost. Also, the present disclosure provides for alloyproducts (e.g. Ti—Al master alloys) that are lightweight and “wool-like”or powdery products. As detailed in paragraph [0068] below, thetemperature and composition of the electrolyte bath appears to influencethe physical form of the titanium-aluminum master alloy formed on thecathode. Temperatures in the range of 550-650° C. tend to result in afine powdery texture, while temperatures in the range of 650-750° C.produce a product with a wool-like morphology, and temperatures in therange of 750-850° C. produce a crystalline product.

It is estimated in 2018 that embodiments of the present disclosure canproduce titanium master alloy (Ti-(1-10) % Al) for $5-6.00/kg whenconsidering today's manufacturing/market conditions.

Technology brought forth by embodiments described in the currentdisclosure provides a novel and straight-forward approach to producetitanium-aluminum alloys from titanium aluminides. This disclosure is anoutgrowth of the patent application “System and Method for Extractionand Refining of Titanium”, issued as U.S. Pat. No. 9,816,192 (Nov. 14,2017) (hereinafter, “the UTRS Process”), which is incorporated herein byreference in its entirety. In some embodiments, the UTRS Process can beused in conjunction with one or more embodiments of the instantdisclosure. However, it is noted that the embodiments of the presentdisclosure are also utilized as a stand-alone technology. One or moreembodiments of the present disclosure provide a cost effective solutionto the production of titanium-aluminum alloys that has heretofore notbeen appreciated.

In one aspect of the present disclosure, a method is provided for theproduction of titanium-aluminum based alloy products, including titaniummaster alloy products, directly from a variety of titanium bearing ores.One or more of the present methods significantly reduce the processingsteps relative to traditional Ti—Al alloy production and result inreduced production costs.

In one aspect of the present disclosure, the method of refiningtitanium-aluminides provides: placing the titanium-aluminide precursorinto a reaction vessel having an anode, a cathode, and an electrolyte,which may include halide salts of alkali metals or alkali-earth metalsor a combination of both, and heating the reaction vessel to atemperature between 500 to 900° C. to create a molten mixture. Anelectric current is applied while maintaining an electrical differentialbetween the anode and the cathode to deposit titanium master alloy onthe cathode.

When the refining process is complete, the current is terminated and themolten mixture is allowed to cool, and the refined titanium master alloyproduct is collected. This refined titanium master alloy productcontains up to 10 wt. % Al (not more than 10 wt. % Al). Indeed, therefined master alloy resulting from the process can contain less than 5wt. % or 2.5 wt. % Al or even less despite the substantial amount ofaluminum present in the titanium aluminide starting material.

In one aspect of the present disclosure, the method of refiningtitanium-aluminides provides: placing the titanium-aluminide precursorinto a reaction vessel, the reaction vessel configured with an anode, acathode, and an electrolyte, which may include halide salts of alkalimetals or alkali-earth metals or a combination of both; heating theelectrolyte to a temperature sufficient to create a molten electrolytemixture (e.g. 500° C. to 900° C.); directing an electrical current fromthe anode through the molten electrolyte mixture to the cathode; andoxidizing the titanium-aluminide precursor from the anode (or dissolvedin ionic form in the molten electrolyte mixture) to form a Ti—Al masteralloy at the cathode.

In some embodiments, the Ti—Al master alloy contains up to 10 wt. % Al.

In some embodiments, the reducing step further comprises depositing theTi—Al master alloy onto a surface of the cathode.

In some embodiments, directing an electrical current comprisesmaintaining an electrical differential between the anode and thecathode.

In some embodiments, the anode is configured to contact and electricallycommunicate with the electrolyte.

In some embodiments, the cathode is configured to contact andelectrically communicate with the electrolyte.

In some embodiments, the anode is positioned in the reaction vessel at adistance from the cathode to prevent electrical shorting of the cell(the anode-cathode distance is variable, but always >0).

In some embodiments, the method comprises terminating the electricalcurrent and turning off the furnace, thereby allowing cooling of themolten electrolyte mixture (e.g. solidifying the electrolyte).

In some embodiments, the Ti—Al master alloy is recovered from the cellprior to solidification (e.g. tapping, draining, withdrawal of thecathode while the bath is cooling but not solidified, or a combinationthereof).

The anode is in the form of a non-consumable mesh container that holdsthe titanium-aluminum-oxygen precursor during the refining process. Theposition of the anode is adjustable; the distance between the anode andthe cathode is between 1 and 6 cm.

The titanium aluminides to be electro-refined may be obtained byreducing titanium-bearing ores with aluminum (e.g., by using the UTRSProcess) or by melting titanium and aluminum scrap metal under oxidizingconditions to produce a product that contains 10 to 25 wt. % Al and atleast 10 wt. % oxygen.

In one aspect of the present disclosure, the method for electro-refiningtitanium-aluminides to produce titanium master alloys provides: placingtitanium-aluminide comprising more than ten weight percent aluminum, andat least ten weight percent oxygen, into a reaction vessel, the reactionvessel configured with an anode, a cathode, and an electrolyte, theelectrolyte including halide salts of alkali metals or alkali-earthmetals or a combination thereof; heating the electrolyte to atemperature of 500° C.-900° C. sufficient to create a molten electrolytemixture; directing an electrical current from the anode through themolten electrolyte mixture to the cathode; and dissolving thetitanium-aluminide from the anode to deposit a titanium-aluminum masteralloy at the cathode.

In some embodiments, the anode includes a non-consumable mesh containerin which the titanium aluminide is placed, the titanium aluminide beingconsumable during the refining process.

In some embodiments, the titanium-aluminide comprises 10%-25% aluminumand at least 10% oxygen by weight.

In some embodiments, the titanium-aluminide comprises 15%-25% aluminumand at least 10% oxygen by weight.

In some embodiments, the titanium-aluminide comprises 20%-25% aluminumand at least 10% oxygen by weight.

In some embodiments, the titanium aluminum master alloy comprises about99.0% titanium and about 1.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about98.0% titanium and about 2.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about97.0% titanium and about 3.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about96.0% titanium and about 4.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about95.0% titanium and about 5.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about94.0% titanium and about 6.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about93.0% titanium and about 7.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about92.0% titanium and about 8.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about91.0% titanium and about 9.0% aluminum by weight.

In some embodiments, the titanium aluminum master alloy comprises about90.0% titanium and about 10.0% aluminum by weight.

In some embodiments, the electrolyte is substantially free of addedtitanium chlorides.

In some embodiments, the electrolyte is substantially free of addedforms of soluble titanium.

In some embodiments, the temperature range is between 550° C. and 650°C. and the titanium master alloy product is a powder.

In some embodiments, the temperature range is between 650° C. and 750°C. and the titanium master alloy product is wool-like.

In some embodiments, the temperature range is between 750° C. and 850°C. and the titanium master alloy product is crystalline.

In some embodiments, the electrical current density of the cathode isbetween 0.0 1A/cm² and 0.05 A/cm².

In some embodiments, the electrical current density of the cathode isbetween 0.05 A/cm² and 0.1 A/cm².

In some embodiments, the electrical current density of the cathode isbetween 0.1 A/cm² and 0.5 A/cm².

In some embodiments, the electrical current density of the cathode isbetween 0.5 A/cm² and 1.0 A/cm².

In some embodiments, a reference electrode is used to monitor electricaldifferentials wherein the electrical differential between the anode andthe reference electrode is 0.2V-0.4V.

In some embodiments, a reference electrode is used to monitor electricaldifferentials wherein the electrical differential between the anode andthe reference electrode is 0.4V-0.6V.

In some embodiments, a reference electrode is used to monitor electricaldifferentials wherein the electrical differential between the anode andthe reference electrode is 0.6V-0.8V.

In some embodiments, the electrical differential between the anode andthe cathode is 0.4V-0.8V.

In some embodiments, the electrical differential between the anode andthe cathode is 0.8V-1.2V.

In some embodiments, the electrical differential between the anode andthe cathode is 1.2V-1.6V.

In some embodiments, the electrical differential between the anode andthe cathode is 1.6V-2.0V.

In some embodiments, the distance between the anode and the cathode isadjusted to prevent short circuiting of the current flow through theelectrolyte between the anode and the cathode.

In some embodiments, the distance between the anode and the cathode is2.0 cm-4.0 cm.

In some embodiments, the distance between the anode and the cathode is4.0 cm-6.0 cm.

In one aspect of the present disclosure, the method for refiningtitanium aluminides into master titanium-aluminum alloys provides:placing a titanium aluminide comprising more than ten weight percentaluminum, and at least ten weight percent oxygen, into a reactionvessel, the reaction vessel configured with an anode, a cathode, and anelectrolyte, the electrolyte including halide salts of alkali metals oralkali-earth metals or a combination of both; heating the electrolyte toa temperature sufficient to create a molten electrolyte mixture;directing an electrical current from the anode through the moltenelectrolyte mixture to the cathode; and dissolving the titaniumaluminide from the anode to deposit a titanium-aluminum master alloy atthe cathode, said master alloy containing up to 10 wt. % aluminum.

In some embodiments, the electrolyte is substantially free of addedtitanium chlorides or other added forms of soluble titanium.

In some embodiments, after the dissolution and deposition step, theelectrolyte is allowed to cool and the titanium-aluminum master alloy isrecovered from the reaction vessel prior to solidification of theelectrolyte.

In some embodiments, the titanium-aluminum master alloy contains 2.5 wt.% or less aluminum.

DETAILED DESCRIPTION

Reference will now be made in detail to the various embodiments of thepresent disclosure. The embodiments are described below to provide amore complete understanding of the components, processes and apparatusesof the present disclosure. Any examples given are intended to beillustrative, and not restrictive.

One embodiment of the present disclosure provides a method for therefining of titanium-aluminide products from titanium-bearing ores.

In the present disclosure, refining of the titanium-aluminide productsis done via electrochemical refining. A titanium-aluminide product isplaced in a reaction vessel having a cathode and an anode. The anode isembodied as a movable perforated basket/container made from quartz ormetals that are more noble than titanium (e.g. nickel or iron) to holdthe titanium aluminide to be refined. The cathode is at or near thebottom of the reaction vessel, with the anode suspended above thecathode. Having the ability to adjust the distance between the cathodeand the anode provides a means of maintaining an optimum distancebetween the cathode and the anode throughout the refining operation.This optimum distance ranges between 1 and 6 cm. The electricaldifferential between the anode and the cathode is between 0.4 and 2.0volts, and the cathode current density is between 0.01 and 1 A/cm².During the refining process, master alloy is deposited on the cathode asdendrites. Growth of the dendrites throughout the process decreases thedistance between the cathode and the anode. Thus, some adjustment indistance may be necessary to maintain current density and to avoid shortcircuiting the current flow. Without adjusting the anode-cathodedistance throughout the process, the dendrites could touch the anodewhich would produce an electrical short-circuit.

The reaction vessel also holds an electrolyte capable of transportingtitanium and aluminum ions. This electrolyte is placed in the reactionvessel and heated to subject the titanium-aluminum product to anelectro-refining process. The electrolyte used during the refiningoperation may be a mixture of MgCl₂-NaCl—suitable for a temperaturerange of 550° C.-650° C., KCl-NaCl—suitable for a temperature range of650° C. to 750° C., or NaCl—suitable for a temperature range of 750°C.-850° C. The refining operation is performed under an inertatmosphere. A resistive element furnace or an induction furnace can beused to heat the electrolyte. In the present disclosure, both types offurnaces (resistive element and induction) have been used. When using aninduction furnace, a molybdenum susceptor crucible was used to couplewith the induction field in order to generate heat that was transmittedto the electrolyte blend. The perforated basket holding the titaniumaluminides to be refined is used as the anode in the electronic circuitby connecting a lead to the positive (+) side of an electric powersupply. Metal foil can be placed around the inside of the reactionvessel and used as the cathode by connecting it to the negative (−) sideof the electric power supply. During operation, the titanium-aluminideis oxidized (ionized) and titanium and aluminum ions migrate to thecathode where they are reduced to form titanium master alloy crystals ora wool layer of the refined titanium-aluminum alloy product. Impuritiesare concentrated (left behind) in the anode basket or remain in themolten electrolyte.

Alternatively, a cathode in the form of a metal plate can be placedparallel to the bottom of the reaction vessel with the anode basketsuspended above the plate. In this configuration, the optimum distancebetween the cathode plate and the anode basket can be maintained bymoving the anode basket vertically throughout the refining operation.The cathode is connected to the negative (−) side of the power supply bythe lead and the anode is connected to the positive (+) side of thepower supply. The cathode to anode distance is between 2 cm and 6 cm.Other configurations for the electro-purification cell are possible aswell.

Titanium-aluminides to be electro-refined can be produced by reducingtitanium bearing ores with Al (e.g., by using the UTRS Process). TiO₂content in titanium bearing ore can be anywhere between 75-98% byweight. Desired composition of titanium-aluminide can be achieved byvarying the TiO₂: Al ratio. As an example, mixing 559 g of a Rutile ore(˜94% TiO₂ content) with 232 g of Al powder and 455 g of CaF₂ willproduce an acceptable blend. Charging the blend into a graphite vessel,ramping the temperature at 10° C/min. (in an argon atmosphere) to ˜1725°C. and soaking for ˜15 min. will produce suitable titanium aluminidemetal that can be used as feed for the electro-refining processdescribed herein.

Titanium-aluminides to be electro-refined can also be produced bymelting titanium and aluminum scrap metals according to appropriateratios.

Samples produced from the following examples were analyzed by usingAtomic Emission Spectroscopy—Direct Current Plasma (DCP-OES) foranalyzing metal concentrations and Inert Gas Fusion (IGF) for analyzingoxygen concentrations. Instruments were calibrated by using NISTstandards. With reference to the following Examples, the cathode depositrefers to the master alloy produced via the various methods, as outlinedin each Example. The percentages of various components are in weightpercent. Unless otherwise specified, the cathode deposit (alloy product)refers to a wt. % Aluminum, the balance being Titanium and if present,any unavoidable impurities.

EXAMPLE 1

Titanium-aluminide used in this example was produced by meltingappropriate amounts of titanium and aluminum to produce Ti-36% Al alloy.Oxygen content of this alloy was 0.2%. The alloy was cut into smallpieces and 29.0 g of this material was electro-refined at a constant DCcurrent of 1.0 A. The refining process was carried out in NaCl-KCl(44:56 wt. %) electrolyte at 750° C. Nine grams (9.0 g) of cathodedeposit was harvested and contained 33wt. % Al.

EXAMPLE 2

Titanium-aluminide used in this example was produced by meltingappropriate amounts of titanium and aluminum to produce a Ti-10% Alalloy. Oxygen content of this alloy was 0.2%. The alloy was cut intosmall pieces and 31.0 g of this material was electro-refined at aconstant DC current of 1.0 A. The refining process was carried out inNaCl-KCl (44:56 wt. %) electrolyte at 750° C. 14.0 g of cathode depositwas harvested and contained 7.0% Al.

EXAMPLE 3

Titanium-aluminide used in this example was produced by aluminothermicreduction of TiO₂ with Al to produce a Ti-13% A1-11% O alloy. The alloywas broken into small pieces and 31.0 g of this material waselectro-refined at a constant DC current of 1.0 A. The refining processwas carried out in NaCl-KCl (44:56 wt. %) electrolyte at 750° C. 18.0 gof cathode deposit was harvested and contained 2.5% Al.

EXAMPLE 4

Titanium-aluminide used in this example was produced by aluminothermicreduction of TiO₂ to produce a Ti-10% A1-13% O alloy. The alloy wasbroken into small pieces and 276.0 g of this material waselectro-refined at a constant DC current of 6.0 A. The refining processwas carried out in NaCl-KCl (44:56 wt. %) electrolyte at 750° C. 96.0 gof cathode deposit was harvested and contained 1.1% Al.

EXAMPLE 5

Titanium-aluminide used in this example was produced by aluminothermicreduction of TiO₂ to produce Ti-13% A1-11% O alloy. The alloy was brokeninto small pieces and 70.0 g of this material was electro-refined at aconstant voltage of 0.8V. The voltage of the anode was controlled byusing a titanium rod as pseudo-reference electrode. The refining processwas carried out in NaCl-KCl (44:56 wt. %) electrolyte at 750° C. 25.0 gof cathode deposit was harvested and contained 2.8% Al.

EXAMPLE 6

Titanium-aluminide used in this example was produced by aluminothermicreduction of TiO₂ to produce Ti-15% Al alloy and electro-refined toproduce a Ti-13% A1-0.7% O alloy. This alloy had wool-like morphology.The alloy was pressed into small pieces and 40.0 g of this material waselectro-refined a second time at a constant voltage of 0.8V. The voltageof the anode was controlled by using a titanium rod as pseudo-referenceelectrode. The refining process was carried out in NaCl-KCl (44:56 wt.%) electrolyte at 750° C. 30.0 g of cathode deposit was harvested andcontained 7.5% Al.

EXAMPLE 7

Titanium-aluminide used in this example was produced by meltingappropriate amounts of titanium, aluminum and iron to produce Ti-10%A1-48% Fe alloy. The alloy was cut into small pieces and 29.0 g of thismaterial was electro-refined at a constant DC current of 1.0 A. Therefining process was carried out in NaCl-KCl (44:56 wt. %) electrolyteat 750° C. 9.0 g of cathode deposit was harvested and contained 17% Aland 1.6% Fe.

EXAMPLE 8

Titanium-aluminide with a composition of Ti-10% A1-12% O waselectro-refined to obtain the composition of Ti-2.7% A1-1.1% O. Therefined material was then once again electro-refined to obtain finalproduct with 99.0% of Ti.

Current efficiency for the electro-refining process depends on the sizeof titanium-aluminide pieces. A current efficiency of 80% is achievedfor the process when less than 4.0 mm pieces were used. Currentefficiency is estimated as a percentage of actually harvested yield totheoretically expected yield. Theoretically expected yield isproportional to total amount of coulombs passed through the system.

Examples 3, 4, 5, and 8 demonstrate that if the precursor materialcontains more than 10% oxygen, a very good separation of titanium andaluminum can be achieved during the electro-refining process. Thetitanium master alloy products in these examples illustrate that morethan 78% of the aluminum in the initial precursor material was removed.In contrast, Examples 1, 2 and 6 demonstrate that not more than 42% ofthe aluminum contained in the precursor material can be removed duringelectro-refining without the presence of a substantial amount of oxygen.

After the refining operation, the resulting refined titanium masteralloy product can be further processed into a final alloy product byadding additional elements. For example, the resulting refined titaniummaster alloy can be ground or milled with vanadium and converted intoTi-Al-V powder.

EXAMPLE 9

56.4 g of Ti-4.6% Al master alloy mixed with 2.8 g of V-Al alloy, 0.55 gAl and melted in VAR. Resulting final alloy had a composition ofTi-6.3A1-3.8V.

The refining operation produces a refined titanium master alloy productwith a finely structured, dendritic morphology. For example, thetitanium master alloy product may comprise titanium crystallites thathave deposited on the cathode during the electro-refining operation. Thefine dendritic structure of the titanium master alloy product uniquelyprovides a pathway for near-net shaped parts through hydrauliccompression and subsequent sintering without the aid of a binding agent.Surface area in the refined titanium-aluminum alloy product rangedbetween 0.1 m²/g and 2.5 m²/g.

Due to the small size and delicate nature of the refined titanium masteralloy product, near-net-shaped products can be compressed for furtherprocessing. The dendritic form of the refined titanium master alloyproduct (titanium master alloy wool) can be compressed by usinghydraulic pressure. To accomplish this, the titanium master alloy woolis placed into a compression mold of desired shape. The mold is thenplaced into a hydraulic press where, between 35 to 65 tons/in² isapplied. This procedure can produce near-net shaped titanium parts thatcan then be sintered, used as consumable electrodes in a vacuum arcremelt (VAR) process, melted or further processed depending on theproduct application.

While specific embodiments of the disclosure have been described indetail, it will be appreciated by those skilled in the art that variousmodifications and alternatives to those details could be developed inlight of the overall teachings of the disclosure. Accordingly, theparticular arrangements disclosed are meant to be illustrative only andnot limiting as to the scope of the disclosure which is to be given thefull breadth of the appended claims and any and all equivalents thereof.

What is claimed is:
 1. A process for electro-refiningtitanium-aluminides to produce titanium master alloys, comprising: a.placing titanium-aluminide comprising more than ten weight percentaluminum, and at least ten weight percent oxygen, into a reactionvessel, the reaction vessel configured with an anode, a cathode, and anelectrolyte, the electrolyte including halide salts of alkali metals oralkali-earth metals or a combination thereof; b. heating the electrolyteto a temperature of 500° C.-900° C. sufficient to create a moltenelectrolyte mixture; c. directing an electrical current from the anodethrough the molten electrolyte mixture to the cathode; and d. dissolvingthe titanium-aluminide from the anode to deposit a titanium-aluminummaster alloy at the cathode.
 2. The process of claim 1 wherein the anodeincludes a non-consumable mesh container in which the titanium aluminideis placed, the titanium aluminide being consumable during the refiningprocess.
 3. The process of claim 1 wherein the titanium-aluminidecomprises 10%-25% aluminum and at least 10% oxygen by weight.
 4. Theprocess of claim 1 wherein the titanium-aluminide comprises 15%-25%aluminum and at least 10% oxygen by weight.
 5. The process of claim 1wherein the titanium-aluminide comprises 20%-25% aluminum and at least10% oxygen by weight.
 6. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 99.0% titanium and about 1.0%aluminum by weight.
 7. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 98.0% titanium and about 2.0%aluminum by weight.
 8. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 97.0% titanium and about 3.0%aluminum by weight.
 9. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 96.0% titanium and about 4.0%aluminum by weight.
 10. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 95.0% titanium and about 5.0%aluminum by weight.
 11. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 94.0% titanium and about 6.0%aluminum by weight.
 12. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 93.0% titanium and about 7.0%aluminum by weight.
 13. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 92.0% titanium and about 8.0%aluminum by weight.
 14. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 91.0% titanium and about 9.0%aluminum by weight.
 15. The process of claim 1 wherein the titaniumaluminum master alloy comprises about 90.0% titanium and about 10.0%aluminum by weight.
 16. The process of claim 1 wherein the electrolyteis substantially free of added titanium chlorides.
 17. The process ofclaim 1 wherein the electrolyte is substantially free of added forms ofsoluble titanium.
 18. The process of claim 1 wherein the temperaturerange is between 550° C. and 650° C. and the titanium master alloyproduct is a powder.
 19. The process of claim 1 wherein the temperaturerange is between 650° C. and 750° C. and the titanium master alloyproduct is wool-like.
 20. The process of claim 1 wherein the temperaturerange is between 750° C. and 850° C. and the titanium master alloyproduct is crystalline.
 21. The process of claim 1 wherein theelectrical current density of the cathode is between 0.01 A/cm² and 0.05A/cm².
 22. The process of claim 1 wherein the electrical current densityof the cathode is between 0.05 A/cm² and 0.1 A/cm².
 23. The process ofclaim 1 wherein the electrical current density of the cathode is between0.1 A/cm² and 0.5 A/cm².
 24. The process of claim 1 wherein theelectrical current density of the cathode is between 0.5 A/cm² and 1.0A/cm².
 25. The process of claim 1 further including the step of using areference electrode to monitor electrical differentials wherein theelectrical differential between the anode and the reference electrode is0.2V-0.4V.
 26. The process of claim 1 further including the step ofusing a reference electrode to monitor electrical differentials whereinthe electrical differential between the anode and the referenceelectrode is 0.4V-0.6V.
 27. The process of claim 1 further including thestep of using a reference electrode to monitor electrical differentialswherein the electrical differential between the anode and the referenceelectrode is 0.6V-0.8V.
 28. The process of claim 1 wherein theelectrical differential between the anode and the cathode is 0.4V-0.8V.29. The process of claim 1 wherein the electrical differential betweenthe anode and the cathode is 0.8V-1.2V.
 30. The process of claim 1wherein the electrical differential between the anode and the cathode is1.2V-1.6V.
 31. The process of claim 1 wherein the electricaldifferential between the anode and the cathode is 1.6V-2.0V.
 32. Theprocess of claim 1 comprising the further step of adjusting the distancebetween the anode and the cathode to prevent short circuiting of thecurrent flow through the electrolyte between the anode and the cathode.33. The process of claim 1 wherein the distance between the anode andthe cathode is 2.0 cm-4.0 cm.
 34. The process of claim 1 wherein thedistance between the anode and the cathode is 4.0 cm-6.0 cm.
 35. Amethod of refining titanium aluminides into master titanium-aluminumalloys, comprising: a. placing a titanium aluminide comprising more thanten weight percent aluminum, and at least ten weight percent oxygen,into a reaction vessel, the reaction vessel configured with an anode, acathode, and an electrolyte, the electrolyte including halide salts ofalkali metals or alkali-earth metals or a combination of both; b.heating the electrolyte to a temperature sufficient to create a moltenelectrolyte mixture; c. directing an electrical current from the anodethrough the molten electrolyte mixture to the cathode; and d. dissolvingthe titanium aluminide from the anode to deposit a titanium-aluminummaster alloy at the cathode, said master alloy containing up to 10 wt. %aluminum.
 36. The method of claim 35 wherein the electrolyte issubstantially free of added titanium chlorides or other added forms ofsoluble titanium.
 37. The method of claim 35 further comprising, afterthe dissolution and deposition step, the steps of allowing theelectrolyte to cool and recovering the titanium-aluminum master alloyfrom the reaction vessel prior to solidification of the electrolyte. 38.The method of claim 35 wherein the titanium-aluminum master alloycontains 2.5 wt. % or less aluminum.